Step-by-step explanation
The equation of the function can be represented as shown as follows:

-This function is discrete.
-If we have 20 gallons, we can obtain the number of miles by plugging in the value into the equation, as shown as follows:

Dividing both sides by 12:

Simplifying:

We can make 1.67 miles with 20 gallons.
-The domain of the function are all the Real Numbers and the Range are also the Real numbers.
-Finally, drawing the graph of the function:
The points of the table are the following:
Gallons Miles
2 24
4 48
6 72
8 96
-We can get the number of gallons needed to, make 500 miles by plugging the value 500 into the equation, as shown as follows:

Isolating m:

Simplifying:

The number of gallons to make 500 miles is equal to 41.7 gallons
Finally, labeling the graph: